Only advantage of buying pre-release is that any new characters released you get for free, anyone else has to pay post release or something along those lines.
btw, whilst the game has the 3rd party EULA on store page, it also hides its privacy rights. You don't get to see these until after you've purchased the game & even then, only once you've installed & launched it.
Save you some hassle, this is where it links to:
https://cdn.battlerite.com/legal/web/privacypolicy.html
No problem if that kind of stuff doesn't bother you, but if it does, at least you know now